Cohesin is a protein that holds chromatids together. Cohesin is established in cell division during S phase and persists through G2 phase and early mitosis. In anaphase, cohesin along the entire length of the chromosome is broken down by an enzyme called separase, allowing the sister chromatids to separate. It is important that separase functions properly so that both the mother cell and daughter cell each get the appropriate number of chromosomes. Forms of cohesin differ between mitosis and meiosis. In meiosis anaphase I, cohesin along the chromosome arms is broken, allowing the two homologs to separate, and cohesin at the centromere is protected by a protein called shugoshin in order to keep the now separated chromosomes to stay together at their respective centromere.
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Precipitation is something that most people regularly experience in their day-to-day lives. While most view it as an annoyance or hinderance, life would not be possible without it. Precipitation is a key step in the water cycle and is a direct result of water evaporation. Precipitation can come in different forms, depending on different weather and atmospheric conditions. In a climate that is above the freezing point of water, rain will be the form of precipitation; however, in cold environments such as New England during the winter, snow is very common. As the weight of the water in the clouds becomes too much, water starts to fall to Earth's surface, and with the temperatures at freezing or below, the water becomes ice crystals and falls as snow. If conditions are particularly windy near the clouds, the ice that falls can be blown back up and collect more ice and keep repeating this until it is too heavy to be blown back up, this is hail. Precipitation can be dangerous, but we should never take it for granted.
In my physics class, we are learning about magnetic fields. One of the most interesting things I find about magnets is the inability to separate north and south poles, unlike the ability to separate positive and negative charges. No matter how small you go, even down to the atom, a magnetized object will always have a magnetic north pole and a magnetic south pole. For example, if you cut a bar magnet with a north and south magnetic pole in half, the two halves would both then form a north and south pole. Scientists have never observed a magnetic monopole, which is a particle that has just one magnetic pole whether that be north or south; however, scientists don't know why this is the case and are trying to figure out why this happens if a magnetic monopole cannot be observed.
Proteins are classified by four levels of structure. The primary structure of a protein is the sequence of amino acids which make up the protein. The protein's secondary structure involves two configurations within the protein. These are referred to as alpha-helices (α helices) and beta-sheets (β-sheets). These are two ways that proteins organize themselves that contribute to their spatial arrangement and three-dimensional shape, which is their tertiary structure. A protein's quaternary structure is the arrangement and number of polypeptide chains within a protein, and therefore only exists if there is more than one polypeptide chain present in the protein. Protein structure is largely determined by intramolecular interactions, as well as the protein's function and where it will be located when it does its job. Proteins generally have a hydrophilic exterior and a hydrophobic interior, due to its environment in the cell containing a lot of water. These interactions help to hold the protein together, otherwise a hydrophobic exterior would denature the protein. By analyzing these aspects of a protein, we can begin to deduce how the protein might function.
Proteins are classified by four levels of structure. Primary structure of a protein is the sequence of amino acids which make up the protein. The protein's secondary structure involves two structures within the protein. These are referred to alpha-helices (α helices) and beta-sheets (β-sheets). These are two ways that proteins organize themselves that contribute to their spatial arrangement and three-dimensional shape, which is their tertiary structure. A protein's quaternary structure is the arrangement and number of polypeptide chains within a protein, and therefore only exists if there is more than one polypeptide chain present in the protein. Protein structure is determined by intramolecular interactions as well as the protein's function and where it will be located when it does its job. Proteins generally have a hydrophilic exterior and a hydrophobic interior, due to its environment in the cell containing a lot of water. These interactions help to hold the protein together, otherwise a hydrophobic exterior would denature the protein. Protein structure tells us a lot about the protein and much can be theorized about its possible function and properties by analyzing the protein structure.
When materials in a lab or hospital need to be sterilized, the most common method to do so is with an autoclave. An autoclave uses steam to sterilize equipment used by surgeons and lab workers. It is the most efficient method of sterilization in terms of power consumption and sterilization efficiency. Other methods like incineration or dry heat sterilization use a lot of fuel and take a long time to sterilize, and often are complicated to operate and require high-level maintenance to run properly, but autoclaves don't go without their specifics too. The steam used in an autoclave can't be too high a temperature or have too much moisture, otherwise the steam cannot penetrate the load to be cleaned well enough and the sterilization is inefficient. Too much moisture in the steam can leave a wet environment after the sterilization, a good environment for bacteria to live if they have not been all killed off. Autoclaves can come in smaller, desktop forms or large devices that can sterilize many tools and devices at once.
Cell splitting is the process in which a cell line is moved to a different flask in order to keep the cell line alive. Cell splitting must be done before the cell population gets too large. If the cell population gets too big, the cells will overcrowd the flask they are in and die as a consequence. In the bioimaging lab, a course I am currently taking. In this class, my lab partner and I are working with a line of LLC-Pk1 epithelial cells., and currently have three flasks of cells for our project. When the time comes for splitting, we follow a specific protocol. First, we prepare the new flask that the cells are going into with medium and correct labeling. We must then remove the medium that is already in the flasks. After that we wash the cells with about 1 mL of warm PBS (phosphate-buffered saline) and after rocking the flask and making sure the PBS has washed thoroughly, the PBS is removed and cells that have died have been removed from the flask. The next step is to add about 0.5 mL of trypsin, and then incubate the flask for about 3 minutes at 37 degrees Celsius. This process removes cells from the bottom of the flask so that they can now be transferred to the next flask. The trypsin reaction is stopped b adding about 1 mL of cold medium to the flask and triturating thoroughly Finally, we can now put 5 or so drops from the old flask into the new flask, where the cells now have more room to grow until they need to be split again.
Seeing in our full range of colors is something a lot people might take for granted daily. A common alternative is a condition called color-blindness, the most common type being red-green color blindness. Color blindness occurs because the color photoreceptors in our eyes, known as cones, have a deficiency in responding to the proper wavelengths of light. Color blindness is therefore not actually a type of blindness, just a deficiency in perceiving color. In red-green color blindness, the affected individual has difficulty distinguishing between red and green, primarily, but color blindness often affects the whole visible color spectrum. This condition is an X-linked recessive disorder, which means that males are more easily affected by this than females. This is because males have one X chromosome and one Y chromosome, and therefore only need one recessive X chromosome from the mother to have this condition. This is different from females that need two copies of the recessive X chromosome, one from each parent. Multiple companies now sell glasses that can correct for the wearer's color blindness. This is the best fix we have currently, as there are no surgical procedures or drugs to take that can help curb the condition.
One of the many ramifications of climate change that is coming to the forefront of the climate change debate is ocean acidification. For many years the primary concern with climate change's effect on the oceans has been the rising sea level that could potentially flood coastal cities and force millions of people to relocate. While this is something that should take focus, ocean acidification is something that is affecting the ocean wildlife, something humans rely a great deal on for food. Besides the food, the ocean also contains many ecosystems that if destroyed can have a chain reaction, destroying other ecosystems that will eventually negatively impact humans. As carbon levels in the atmosphere increase, carbon dioxide diffuses into the ocean. Carbon dioxide likes to react with calcium carbonate, the material used to make shells and coral reefs, to make carbonic acid. As more and more carbon dioxide gets into the ocean, the more carbonic acid is created, lowering the pH level of the ocean to a more acidic level. Organisms in the ocean require certain conditions to thrive, and as the pH gets lower organisms cannot thrive in such acidic conditions. This is evident in coral reefs, where a process called coral bleaching is occurring. The acidic water makes the coral expel the algae that usually lives in, and has an endosymbiotic relationship with the coral. The loss of the algae produces a sickly white color (hence "bleaching"). Ocean acidification is just one cause of coral bleaching. Humans must crack down immediately to save our planet.
Flight is one of the most involved adaptations an organism can have. What that means is that when an organism is on the evolutionary path to flight, everything else about that organism's morphology/lifestyle must change to accommodate the ability to fly. The bones must become lightweight, and habitat is most likely at a high altitude. Organisms evolving for flight have to make themselves as light as possible, meaning that heavy feathers are not a good option. The body must become streamlined in order to get the best possible flying efficiency, or face losing energy to fight additional air resistance from a non-aerodynamic body. Flying has only evolved once in mammals: the bat. The bat has a lightweight skeleton with long, thin arms that provide the framework for their wingspan. Unlike most flying animals, their eyesight can actually be very poor, and some species of bats rely on echolocation to fly around and locate prey. Flying is an all-in, evolutionary commitment, and a lifestyle that has been lived out successfully by many thousands of animals.